Green light for Carmacks copper project

Western Copper Corp. cleared an important hurdle July 21 in the permitting process for its Carmacks copper project 38 kilometers, or nearly 24 miles, northwest of the town of Carmacks in central Yukon.

The Executive Committee of the Yukon Environmental and Socioeconomic Assessment Board released a final screening report for the proposed Carmacks Copper Project that concluded the project may go ahead without further YESAB review.

The decision paves the way for Western Copper to obtain a quartz mining license and move ahead with its development plans, company officials said.

The Carmacks project has a measured and inferred oxide resource of 12 million metric tons grading 1.07 percent copper, 0.46 grams per metric ton gold and 4.6 g/t silver. In sulphides it has a further 4.3 Mt grading 0.75 percent copper, 0.22 g/t gold and 2.4 g/t silver.

In a feasibility study completed in May 2007, Western Copper outlined a plan for an open pit mine with a 6-year mine life (later increased to 7 years with potential for expansion) using acid heap-leach, solvent extraction and electrowinning for a final end product of London Metal Exchange grade A copper cathode.

Western Copper estimated a proven and probable resource of 10.6 Mt grading 1.04 percent copper, 0.48 g/t gold and 4.6 g/t silver.

Capital costs totaled C$144 million, with the Canadian dollar at 85 cents American. With the Canadian dollar at parity, costs would decrease to $131 million.

Environmental measures adequate

The YESAB report includes an assessment of the project's effects on soil, air, water and wildlife, as well public and worker health and safety, heritage resources and local communities. In essence, YESAB is satisfied with Western Copper's environmental plan for the project.

Jonathan Clegg, vice president, engineering for Western Copper, told Mining News June 27 that the company hopes the YESAB decision will alleviate the concerns local residents and members of area First Nations groups have expressed about potential adverse effects on nearby rivers and streams of the detoxification method proposed for the project.

Clegg said the Carmacks project is the first big venture "for YESAB to sink their teeth into."

"We'd like things to move faster, but we can't criticize how they've looked at the project," he said.

The regulatory board considered a wide range of potential impacts and addressed issues raised by First Nation governments, Yukon government, nonprofit organizations, the public and local experts in preparing the screening report.

"We've spent a lot of time on this assessment," said Stephen Mills, a member of the YESAB Executive Committee. "Closure and reclamation issues had to be reviewed in great detail. We had to be sure that the detoxification plan would prevent any toxic effluent from leaking into the Yukon River system."

Other areas of focus included the effect of local traffic from the mine, water quality, heritage resources, community dynamics and fish habitat.

"Maintaining the health and well-being of salmon and their habitat is always imperative," Mills said in a July 21 statement. "Yukoners made it very clear that the water of the Yukon River and salmon stocks are highly valued."

The report now goes to Canadian and Yukon regulators who will make a final decision on the project and issue permits.

Acid-consuming rock helps

Ironically, the likelihood of acid drainage from the Carmacks deposit is relatively low because the host rock is acid-consuming, which means water draining from the site will be somewhat neutralized by natural forces.

Western Copper plans to mine only the oxide mineralization at Carmacks, which is fairly evenly distributed over the top of a rolling hill and adjacent plateau.

The oxide cap goes down about 250 meters, and the company plans to stop short of the interface with sulphide, or acid-generating, rock below, Clegg said during a visit to the project site June 27.

The area at the bottom of the open pit will be 30 meters wide and 800 meters long, and actually will be below the level of nearby Williams Creek, he added. This means drainage from the pit would have to run uphill to reach the creek.

Western Copper's development plan also calls for using conventional acid heap leach technology that involves rinsing the heap to neutralize acid in it at the end of the mine's life.

"Our estimate is that with five years of rinsing, we could have water with a PH in the 4-5 range coming out of the heap," Clegg said. The process will include plain water and a soda ash rinse, which almost immediately neutralizes acid in the heap.

"This is not new technology, and at the end of the day, the truth will survive," said Michael Burke, acting director of the Yukon Geological Survey.

Deeper ore may be in mine's future

Western Copper may eventually choose to mine the deeper sulphide ore at Carmacks, but that would likely involve a different approach, perhaps an underground operation, said Scott Casselman, a geologist who is working on the Carmacks project as a consultant.

"Right now, most of our drilling is focused on the oxide zone, so as soon as we get into sulphides, we stop drilling," Casselman said.

Western Copper hopes to begin construction in 2009 and copper production in the late third quarter or early fourth quarter of 2010. The quartz mining license will enable construction to begin, but the company must obtain a Type A Water license to complete construction of the mine and begin copper production.